Some standard content:
National Standard of the People's Republic of China
Code for design of levee project
Code for design of levee projectGB50286—98
Competent department: Ministry of Water Resources of the People's Republic of ChinaApproving department: Ministry of Construction of the People's Republic of ChinaEffective date: October 15, 1998
Notice on Issuing the National Standard
"Code for Design of Levee Project"
Jianbiao [1998] No. 185
In accordance with the requirements of the "1992 Engineering Construction Standard Formulation and Revision Plan" (Appendix 2 to Document No. 490 of the State Planning Commission [1992]), the "Code for Design of Levee Project" jointly formulated by the Water Resources Department and relevant departments has been reviewed and approved as a mandatory national standard by the relevant departments, with the number GB50286-—98, and will be implemented on October 15, 1998. This specification is managed by the Ministry of Water Resources, interpreted by the Ministry of Water Resources Water Resources and Hydropower Planning and Design Institute, and published by the Ministry of Construction Standards and Norms Research Institute and China Planning Press.
Ministry of Construction of the People's Republic of China
October 8, 1998
The national standard "Embankment Engineering Design Specification" is edited by the Ministry of Water Resources in accordance with the requirements of the "1992 Engineering Construction Standard Formulation and Revision Plan" issued by the State Planning Commission in 1992 with the number of C927490, and is specifically compiled by the Ministry of Water Resources Water Resources and Hydropower Planning and Design Institute, the Ministry of Water Resources Yellow River Water Resources Commission, Guangxi Autonomous Region Water Resources Department and other 12 units. This specification was reviewed by relevant departments, approved by the Ministry of Construction with the document No. Jianbiao (1998) 185, and jointly issued with the State Administration of Quality and Technical Supervision. During the preparation of this specification, the preparation team conducted extensive investigations and studies, carefully summarized the practical experience of my country's levee engineering construction, widely solicited opinions from relevant units and experts across the country, and retrieved and referenced relevant design indicators and advanced standards of major foreign countries. This specification is managed by the Ministry of Water Resources, and the specific interpretation work is the responsibility of the Ministry of Water Resources Water Resources and Hydropower Planning and Design Institute. During use, all units should actively summarize experience and send opinions to the National Standard "Embankment Engineering Design Specification" Management Group of the Ministry of Water Resources Water Resources and Hydropower Planning and Design Institute (Address: Liupukang, Ande Road, Beijing, Postal Code: 100011) for reference during revision. The chief editor of the national standard "Embankment Engineering Design Specification": Ministry of Water Resources Water Resources and Hydropower Planning and Design Institute. Participating units: Yellow River Conservancy Commission of the Ministry of Water Resources, Guangxi Autonomous Region Water Resources Department, Heilongjiang Provincial Water Conservancy and Hydropower Survey and Design Institute, Henan Yellow River River Affairs Bureau, Shandong Yellow River Survey and Design Institute, Jiangsu Provincial Water Conservancy Survey and Design Institute, Hubei Provincial Water Conservancy Survey and Design Institute, Hunan Provincial Water Conservancy Survey and Design Institute, Guangdong Provincial Water Conservancy Survey and Design Institute, Hohai University, Information Research Institute of the Ministry of Water Resources, etc. The main drafters who participated in the preparation of this specification: Wang Zhongli, Bin Guang, Song Yujie, Xu Yongjiu, Wang Guanping, Yu Qiangsheng, Pan Shaohua, Wang Qingsheng, Yang Shulin, Wu Weimin, Luo Guifen, Wen Yihuai, Chen Yintai, Li Weitao, Yan Yueling, Xie Youlong, Han Liyu. 256
1.0.1 In order to meet the needs of levee construction, unify the design standards and technical requirements of levee projects, achieve advanced technology, economic rationality, safety and applicability, and enable levee projects to effectively defend against floods and tidal hazards, this specification is formulated. 1.0.2 This code is applicable to the design of all types of new, reinforced, expanded and rebuilt embankment projects. 1.0.3 The design of embankment projects shall be based on the comprehensive planning of rivers, lakes and coastal zones or professional planning for flood control and tide prevention. The design of urban embankment projects shall also be based on the overall urban planning. 1.0.4 The design of embankment projects shall have reliable basic data such as meteorology and hydrology, topography and geomorphology, water system and water area, geology and social economy. The design of embankment reinforcement and expansion shall also have data such as the current status and application of embankment projects. 1.0.5 The design of embankment projects shall meet the requirements of stability, seepage, deformation and other aspects. 1.0.6 The design of embankment projects shall implement the principle of adapting measures to local conditions and using local materials, and actively and prudently adopt new technologies, new processes and new materials. 1.0.7 Class 1 embankment projects located in areas with a seismic intensity of 7 degrees or above shall be subject to anti-tide design with the approval of the competent authorities. 1.0.8 In addition to complying with this code, the design of embankment projects shall also comply with the provisions of the relevant current national standards. 2 Levels and design standards for levee projects
2.1 Flood control standards and levels for levee projects
2.1.1 The flood control standards for the objects protected by levee projects shall be determined in accordance with the current national standard "Flood Control Standards". The flood control standards for levee projects shall be determined based on the flood control standards of the objects with higher flood control standards within the protection area. The level of levee projects shall comply with the provisions of Table 2.1.1. Table 2.1.1 Level of embankment works
Flood control standards [current period (years)
Level of embankment works
≥100
<100 and ≥50
50 and ≥30
<30. and ≥20
<20, and ≥10
2.1.2 For embankment works that suffer huge losses and serious impacts after floods or accidents, their levels can be appropriately increased, and for temporary embankment works that suffer small losses and impacts after floods or accidents or have a short service life, their levels can be appropriately reduced. Embankment works that adopt levels higher or lower than the specified level should be reported to the competent industry department for approval, and when it affects public flood control safety, it should also be reported to the water administration department for approval. 2.1.3 For rural protection areas of seawalls, when the population is dense, rural enterprises are relatively developed, and crops are highly productive or aquaculture output is high, the flood control standards can be appropriately raised, and the level of the seawall should also be raised accordingly. 2.1.4 The flood control standards for embankment projects in flood storage and detention areas should be specifically determined in accordance with the requirements of the approved flood control plan for the city or the regional flood control plan. 2.1.5 The design flood control standards for buildings and other structures such as gates, culverts, pump stations, etc. on embankment projects should not be lower than the flood control standards for embankment projects, and appropriate safety margins should be left. 2.2 Safety height increase value and stability safety factor
2.2.1 The safety height increase value of embankment projects should be determined according to the level of embankment projects and wave protection requirements in accordance with the provisions of Table 2.2.1. The safety height increase value of important embankment sections of Class 1 embankments can be appropriately increased after demonstration, but shall not be greater than 1.5m. 257
Safety height increase value
Grade of dike project
Table 2. 2. 1
Dyke project not allowed to overrun
Dyke project allowed to overrun
Safety height increase value of dike project
2.2.2 The allowable slope of non-cohesive soil to prevent seepage deformation shall be determined by dividing the critical slope of the soil by the safety factor, and the safety factor shall be 1.5~2.0. When there is no test data, the allowable slope of non-cohesive soil can be selected according to Table 2.2.2, and can be appropriately increased when there is a filter layer. For particularly important dike sections, the allowable slope shall be determined based on the critical slope of the test. Table 2.2.2 Allowable slope of cohesionless soil
Permeability
Shape
Allowable slope
Note: 1.Cu-
Unevenness coefficient of soil,
Flow soil type
3≤C≤5
0.35~0.50
2.The values in the table are applicable to the case where there is no filter layer at the fall outlet. Cu>5
0. 50～0.80
2.2.3 The anti-sliding stability safety factor of the earth embankment should not be less than the provisions of Table 2.2.3. Transition type
0. 25~~0. 40
Table 2. 2. 3 Safety factor of earth embankment anti-sliding stability Class of embankment engineering
Normal operating conditions
Safety factor
Extraordinary operating conditions
Piping type
Continuous gradation
0. 15~0.25
Discontinuous gradation
0.10~0.15
2.2.4 When the anti-sliding stability safety factor of earth embankments on coastal weak embankment foundations is difficult to reach the specified value, it can be appropriately reduced after demonstration and approval by the competent industry department.
2.2.5 The anti-sliding stability safety factor of flood control walls should not be less than that specified in Table 2.2.5. Table 2.2.5 Safety factor of flood wall anti-sliding stability Foundation properties
Level of levee engineering
Normal operating conditions
Emergency operating conditions
The safety factor of flood wall anti-tilting stability should not be less than that specified in Table 2.2.6. 2.2.6
Table 2.2.6 Safety factor of flood wall anti-tilting stability Level of levee engineering
Normal operating conditions
Safety factor
Emergency operating conditions
3 Basic information
3.1 Meteorology and hydrology
3.1.1. The design of levee projects should be equipped with meteorological and hydrological data such as temperature, wind conditions, evaporation, precipitation, water level, flow, flow velocity, sediment, tide, wave, ice conditions, groundwater, etc.
3.1.2 The design of levee projects should be equipped with data such as water system, water distribution, river regime evolution and scouring and silting changes in the areas related to the project. 3.2 Social Economy
The design of levee projects should be equipped with social and economic data of levee protection areas and levee project areas. The social and economic data of levee project protection areas should include the following: 3.2.2
Social profiles such as area, population, cultivated land, and urban distribution; 1
2 National economic profiles such as scale, assets, output, and output value of agriculture, industrial and mining enterprises, transportation, energy, communications, etc. 3 Ecological and environmental conditions;
Historical flood and tidal disasters.
The socio-economic data of the dike project area shall include the following: 3.2.3
Land, cultivated land area, population, houses, fixed assets, etc. 2Agriculture, forestry, animal husbandry, industrial and mining enterprises, transportation, communication, cultural education and other facilities; 3Cultural relics, tourist facilities, etc.
3.3 Engineering topography
3.3.1 The topographic survey data of the dike project at different design stages shall comply with the provisions of Table 3.3.1. Table 3.3.1 Mapping requirements for embankment engineering at various design stages Map type
Topographic map
Longitudinal section
Cross section
Working stage or
Design stage
Preliminary design
Preliminary design
Scale
1 : 10000~11 50000
1 : 1000~1 1 10000
Vertical 1#100~1#200
1: 10000~1: 50000
Vertical 1:100
Horizontal 1500～1*1000
Map sheet range and section spacing
From the center line of the embankment to both sides
The sandy soil embankment foundation should be wider on the backwater side. If the strip is expanded 100~, the water side is an erosional beach, it should be expanded to 300m
Every 50~200m
section, measuring 200~
width outside the deep erosion line
When the length of the line exceeds 100km, the horizontal scale can be 150000~1
100000
The section spacing of the curve section should be reduced.
When the cross-sectional width exceeds 500m, the horizontal scale can be 12000. The horizontal scale of the old embankment reinforcement can also be
3.3.2 New embankment projects should provide a longitudinal section of the embankment centerline; reinforcement and expansion projects should also provide longitudinal sections of the embankment top and the front and back embankment footings.
3.4 Engineering Geology
3.4.1 The engineering geology and embankment material data for the design of embankment projects of level 3 and above shall comply with the provisions of the current national standard "Embankment Engineering Geological Survey Regulations". The engineering geology and embankment material data for the design of embankment projects of levels 4 and 5 can be appropriately simplified. When conditions permit, relevant data on nearby projects can also be cited.
3.4.2 The design of embankment projects should make full use of the geological survey data of existing embankment projects and construction projects on the embankment line. The historical and current dangerous information of dangerous construction sites should be collected to find out the scope, stratum and plugging materials of historical breached dike sections. 4 Dike line layout and dike type selection
4.1 Dike line layout
4.1.1 The dike line layout should be determined by comprehensive analysis after technical and economic comparison based on flood control planning, topography, geological conditions, river or coastline changes, combined with the location of existing and planned buildings, construction conditions, existing engineering conditions, land acquisition and demolition, cultural relics protection, administrative divisions and other factors. 4.1.2 The dike line layout should follow the following principles: 1 The river dike line should be adapted to the river flow direction and roughly parallel to the mainstream line of the flood. The distance between the dikes on both sides of a river section or the distance between the high ground on one side and the dike on the other side should be roughly equal, and should not be suddenly enlarged or reduced. 2 The dike line should be smooth, and each dike section should be smoothly connected. No broken lines or sharp bends should be used. 3 The dike project should make full use of existing dikes and favorable terrain, and be built on the beach with good soil and relatively stable, leaving a beach of appropriate width, and avoid weak foundations, deep water areas, ancient river channels, and highly permeable foundations as much as possible. 4 The dike line should be arranged in areas with few buildings such as occupied cultivated land and demolished houses, avoid cultural relics, and facilitate flood prevention and engineering management.
5 Lake dikes and sea dikes should avoid strong winds or tides as much as possible. 4.1.3 The dike line layout of tidal flat dikes, estuary dikes and other important dike sections should be coordinated with the regional economic and social development plan, and the impact on the ecological environment and social economy should be analyzed and demonstrated. Model tests should be carried out when necessary. 4.2 Determination of river embankment distancewww.bzxz.net
4.2.1 The distance of newly built river embankments shall be determined according to the flood control plan of the river basin and by river section, and the upstream and downstream and left and right banks shall be taken into consideration. 4.2.2 The distance of river embankments shall be determined after comprehensive analysis and weighing of relevant natural and social factors based on the topography and geological conditions of the river channel, the hydrological and sediment characteristics, the evolution characteristics of the riverbed, the laws of scouring and silting, and the technical and economic indicators of different embankment distances. 4.2.3 When determining the distance of river embankments, room shall be left based on the requirements of social and economic development, the limitations of the existing hydrological data series, the long-term flood retention and siltation in the beach area, and the protection of the ecological environment. 4.2.4 In the case of narrow river sections whose flood discharge capacity is significantly smaller than that of the upstream and downstream sections due to the influence of mountain mouths, reefs or other buildings and structures, measures shall be taken to widen the embankment distance or remove obstacles.
4.3 Selection of embankment type
4.3.1 The type of embankment project should be determined comprehensively according to the principle of adapting measures to local conditions and using local materials, based on the geographical location, importance, embankment site 260
geology, embankment materials, water flow and wind and wave characteristics, construction conditions, application and management requirements, environmental landscape, project cost and other factors after technical and economic comparison.
4.3.2 According to the embankment materials, earth embankment, stone embankment, concrete or reinforced concrete flood control wall, mixed material embankment with partition filling, etc. can be selected; according to the cross-sectional type of the embankment, slope embankment, straight embankment or straight-sloped composite embankment, etc. can be selected; according to the design of the impermeable body, homogeneous earth embankment, inclined wall type or core wall type earth embankment, etc. can be selected.
4.3.3 Different embankment types can be used for each embankment section of the same embankment line according to specific conditions. Connection treatment should be done well at the place where the embankment type changes, and a transition section should be set up if necessary.
5 Foundation treatment
5.1 General provisions
5.1.1 The foundation treatment should be based on the level of the embankment project, embankment height, foundation conditions and seepage control requirements, and an economically reasonable plan should be selected. 5.1.2 The foundation treatment should meet the following requirements of seepage control, stability and deformation. 1 Seepage control should ensure the seepage stability of the embankment foundation and the outer soil layer of the backwater side embankment foot; static stability calculations should be carried out for the stability of the embankment foundation. For embankments built according to earthquake resistance requirements, dynamic stability calculations should also be carried out for their foundations; 2
After completion, the total settlement and uneven settlement of the embankment foundation and embankment body should not affect the safe use of the embankment. 3
5.1.3 Hidden dangers such as culverts, old river channels, collapsed areas, animal nests, graves, holes, ponds, wells, house foundations, and miscellaneous fill in the embankment foundation should be explored and treatment measures should be taken.
5.2 Treatment of weak embankment foundation
5.2.1 The physical and mechanical properties and anti-seepage strength of soft embankment foundations such as soft clay, collapsible loess, liquefiable soil, expansive soil, peat soil and dispersed clay, as well as their possible impact on the project, should be studied. 5.2.2 Treatment measures for soft clay embankment foundation: Shallow thin layers of soft clay should be excavated; when the thickness is too large to be excavated or it is not economical to excavate, methods such as paving permeable materials to accelerate drainage and diffuse stress, setting ballast outside the embankment foot, digging drainage wells or plastic drainage belts, slowing down the embankment slope, and controlling the construction loading rate can be used. The calculation of cushion layers, drainage wells, ballast, etc. shall comply with the provisions of Appendix A of this Code. 5.2.3 When paving permeable materials to accelerate the drainage and consolidation of soft soil is used for soft clay embankment foundation, the permeable materials can be gravel, crushed stone, geotextile, or a combination of the two. In the anti-seepage body, the creation of seepage channels should be avoided. 5.2.4 When building embankments on soft clay foundations, the continuous construction method is used. When the filling height reaches or exceeds the height that the soft clay foundation can bear, ballast can be set outside the embankment foot. When the first-level ballast does not meet the requirements, two-level ballast can be used. The height and width of the ballast should be determined by stability calculations. 5.2.5 Drainage sand wells and plastic drainage belts can be used to accelerate consolidation of soft clay foundations. Drainage wells should be used in conjunction with permeable cushion layers. When there is pressurized water under the soft clay layer, drainage and penetration of the soft soil layer should be prevented. 5.2.6 The method of controlling the filling rate can be used to build embankments on soft clay foundations. The filling rate and intermittent time should be determined by calculation, testing or combined with similar engineering analysis.
5.2.7 When building important embankments on soft clay foundations, the foundation can be reinforced by methods such as vibratory flushing or mixing piles. 5.2.8 When building embankments on collapsible loess foundations, the pre-immersion method or the surface heavy hammer compaction method can be used. When building higher or important embankments on highly collapsible loess foundations, special treatment measures should be studied. 5.2.9 Embankments with anti-expansion requirements should be implemented in accordance with the relevant provisions of the current national standard "Code for Anti-water Design of Hydraulic Structures". 5.2.10 For liquefiable soil layers that must be treated, when excavation is difficult or uneconomical, artificial densification measures can be taken. For shallow liquefiable soil layers, surface gripping and compaction measures can be used; for deep liquefiable soil layers, vibration flushing, strong tamping, and the installation of sand and gravel piles to strengthen embankment foundation drainage can be used. 261
5.2.11 If peat soil cannot be avoided and excavated, appropriate measures should be taken according to the compressibility of the peat soil. If conditions permit, indoor tests and experimental filling should be carried out.
5.2.12 For expansive soil embankment foundation, excavation, enclosure, ballasting and other methods can be used to treat it based on the properties and distribution range of the expansive soil. 5.2.13 For dispersed clay embankment foundation, lime should be added to the part below the impermeable body of the embankment. The amount of lime should be determined by test according to the soil conditions. The weight ratio can be 2% to 4%. The treatment depth of homogeneous soil embankment can be 0.2 to 0.3m, and the core wall or inclined wall earth-rock embankment can be 1.0 to 1.2m below the impermeable body. In non-impermeable body parts, a filter layer that meets the requirements for protecting dispersed clay can be used. 5.3 Permeable embankment foundation treatment
5.3.1 The shallow permeable embankment foundation should adopt clay soil interception ditch or other vertical anti-seepage measures to intercept seepage. The bottom of the interception ditch should reach a relatively impermeable layer. The interception ditch should be filled with the same soil material as the impermeable body of the embankment, and its compaction density should not be less than the same soil material of the embankment. The bottom width of the intercepting ditch should be determined according to the backfill soil, the allowable seepage gradient of the underlying relatively impermeable layer and the construction conditions. 5.3.2 For embankments with deep relatively impermeable layers, thick permeable layers and stable beaches on the water side, blanketing anti-seepage measures should be adopted. The length and section of the blanket should be determined by calculation. When calculating, the seepage stability of the underlying layer and the blanket itself should be calculated. When using a natural weak permeable layer as an anti-seepage blanket, the distribution, thickness, gradation, permeability coefficient and allowable seepage gradient of the natural weak permeable layer and the underlying permeable layer should be found out. Artificial blanket reinforcement measures should be adopted in areas where natural blanketing is insufficient. In places where there is a lack of blanketing soil, geomembranes or composite geomembranes can be used, and a protective layer and exhaust and drainage system should be set on the surface. 5.3.3 For important sections on the deep and permeable embankment foundation, underground cut-off walls made of clay, geomembrane, solidified mortar, concrete, plastic concrete, asphalt concrete, etc. can be set up. The depth and thickness of the cut-off wall should meet the requirements of the allowable seepage slope of the embankment foundation and wall materials. 5.3.4 When a particularly important embankment section needs to build a grouting curtain in the gravel embankment foundation, the pourability of the embankment foundation should be determined through indoor and field tests. For embankments with poor pourability of granular material slurry, chemical grouting can be used, or chemical grouting can be used after grouting the granular material. When using a grouting curtain, the relevant provisions of the current national standard "Technical Specifications for Cement Grouting Construction of Hydraulic Structures" can be followed. The calculation method should comply with the provisions of Appendix A of this code. 5.4 Multi-layer embankment foundation treatment
5.4.1 Multi-layer embankment foundation treatment measures can include measures such as adding a cover on the backwater side of the embankment, drainage pressure relief ditch, drainage pressure relief well, etc. Treatment measures can be used alone or in combination.
5.4.2 For foundations with thick surface aquitard, it is advisable to adopt weight-covering measures. The weight-covering should be made of permeable materials. The calculation method should comply with the provisions of Appendix A of this Code.
5.4.3 For foundations with thin surface aquitard, if the underlying aquitard is basically uniform and thick enough, it is advisable to adopt drainage and pressure relief ditches. Drainage and pressure relief ditches can be open ditches or concealed ditches. Concealed ditches can be made of sandstone, geotextiles, perforated pipes, etc. 5.4.4 For foundations with thin surface aquitard, if the underlying aquitard is layered and anisotropic, and the strong aquitard is located at the bottom of the foundation, or if there are thin clay layers and lenses in between, drainage and pressure relief wells should be adopted. The well spacing and depth should be reasonably determined according to the seepage control requirements and the formation conditions, combined with construction and other factors.
5.4.5 The plane position of drainage and pressure relief ditches and drainage and pressure relief wells should be close to the toe of the backwater side of the embankment. 5.4.6 After setting up drainage pressure relief ditches and drainage pressure relief wells, the seepage gradient of the embankment foundation and the seepage outlet should be reviewed. When the permissible seepage gradient is exceeded, other anti-seepage and anti-filtration measures should be taken. Anti-seepage and anti-filtration can use natural materials or geomembranes, geotextiles, etc. 5.5 Anti-seepage treatment of rock embankment foundation
5.5.1 The rock embankment foundation should be treated with anti-seepage treatment when one of the following conditions exists. 1 Strongly weathered or cracked rocks may cause seepage damage to the rock or embankment body. 2 Due to karst and other reasons, the amount of seepage is too large, which may endanger the safety of the embankment. 262
5.5.2 When the rock embankment foundation is strongly weathered and may cause seepage damage to the rock embankment foundation or embankment body, the rock cracks under the anti-seepage body should be sealed with mortar or concrete, and a filter layer should be set downstream of the anti-seepage body. Filter material should be used to cover the non-anti-seepage body. 5.5.3 In karst areas, after the situation is clarified, the leakage channel should be filled according to the local material conditions, and anti-seepage blankets can be added if necessary.
5.5.4 When setting up the grouting curtain on the embankment section on the rock embankment foundation, it can be implemented according to the current national standard "Technical Specifications for Cement Grouting Construction of Hydraulic Structures".
6 Embankment Design
6.1 General Provisions
6.1.1 The embankment structure should be economical and practical, made of local materials, easy to construct, and should meet the requirements of flood control and management. 6.1.2 The embankment design should be carried out in sections according to the embankment foundation conditions, embankment materials and operation requirements. The structure and size of each part of the embankment should be determined after stability calculation and technical and economic comparison.
6.1.3 The design of the earth embankment body should include the determination of the embankment cross-section layout, filling standards, embankment top elevation, embankment top structure, embankment slope and platform, slope protection and slope drainage, anti-seepage and drainage facilities, etc.
The design of flood control walls should include the determination of the wall structure type, wall top elevation, foundation wheel size, anti-seepage and drainage facilities. 6.1.4 The cross-section of the embankment body that passes through old river channels, embankment breach repairs, seawall port repairs, etc. should be determined after special research based on conditions such as water flow, embankment foundation, construction methods and embankment materials, combined with practical experience from various places. 6.2 Embankment materials and earth embankment filling standards
6.2.1 The selection of embankment materials such as soil, stone and gravel should comply with the following provisions: 1 Soil material: Sub-clay should be used for homogeneous earth embankments. The clay content should be 15%~30%, the plastic index should be 10~20, and it should not contain impurities such as plant roots, bricks and tiles, garbage, etc. The allowable deviation between the moisture content of the filling soil and the optimal moisture content is ±3%. The anti-seepage bodies such as blankets, core walls, and inclined walls should use soil with greater viscosity. The back cover of the embankment should be made of sandy soil; 2 Stone: good weathering resistance, freeze-thaw loss rate less than 1%; the mass of the wall stone can be 50~150kg, and the mass of the embankment slope protection stone can be 30~50kg; the shape of the stone should be a rectangular parallelepiped with a masonry surface, and the side length ratio should be less than 4; 3 Sand and gravel: weathering resistance, good water stability; the mud content should be less than 5%, 4 Concrete aggregate should comply with the relevant provisions of the current national standard "Regulations for the Investigation of Natural Building Materials for Water Conservancy and Hydropower Projects". 6.2.2 The following soils are not suitable for embankment filling. When necessary, corresponding treatment measures should be taken: 1 Silt or clay with a high natural moisture content and excessive clay content, 2 Fine sand,
3 Frozen soil blocks;
4 Expansive soil and dispersed soil with poor water stability. 6.2.3 When taking measures such as processing soil materials or reducing the design dry density, such as large embankment sections and slowing down slopes, they should be determined after technical and economic comparisons.
6.2.4 The filling density of earth embankments shall be determined by comprehensive analysis based on factors such as embankment level, embankment structure, soil material characteristics, natural conditions, construction machinery and construction methods.
6.2.5 The filling standard of cohesive soil embankments shall be determined according to the compaction degree. The compaction value shall comply with the following provisions: 11-level embankments shall not be less than 0.94;
22-level embankments and 3-level embankments with a height of more than 6m shall not be less than 0.92263
33-level embankments and 3-level embankments below 6m shall not be less than 0.90. 6.2.6 The filling standard of non-cohesive soil embankments shall be determined according to the relative density. 1, 2-level embankments and 3-level embankments with a height of more than 6m shall not be less than 0.65; 3-level embankments and 3-level embankments below 6m shall not be less than 0.60. Embankments with earthquake resistance requirements shall be implemented in accordance with the relevant provisions of the current national standard "Code for Anti-slope Design of Hydraulic Structures". 6.2.7 For breach repair, port-to-port repair, underwater embankment, and earth embankment on weak embankment foundation, the design fill density should be determined based on the construction method adopted, soil material properties and other conditions and combined with the fill density analysis of similar embankment projects that have been built. 6.3 Embankment top elevation
6.3.1 The levee crest elevation shall be determined by the design flood level or the design high tide level plus the levee crest superelevation. The design flood level shall be calculated in accordance with the provisions of the relevant national standards in force. The design high tide level shall be calculated in accordance with Appendix B of this Code. The levee crest superelevation shall be determined by the following formula. The levee crest superelevation value of Class 1 and Class 2 levees shall not be less than 2.0m.
Y-R+e+A
WuzhongY—
Dike crest superelevation (m);
R—design wave run-up (m), which can be determined by calculation in Appendix C; (6.3.1)
e—design wind-fall surge height (m), which can be determined by calculation in Appendix C; for seawalls, when the design high tide level includes the wind surge height, it shall not be calculated separately,
A—safety height increase (m), which shall be determined in accordance with Table 2.2.1 of this Code. 6.3.2 For river sections prone to ice jams and ice dams during the flow period, the embankment top elevation shall be calculated in accordance with Article 6.3.1 of this Code, and shall also be determined after special analysis and demonstration based on historical ice flood water levels and wind and wave conditions. 6.3.3 When a stable and solid wave-breaking wall is installed on the shoulder of the earth embankment facing the water, the calculation of the wave-breaking wall top elevation shall be the same as the calculation of the embankment top elevation in Article 6.3.1, but the elevation of the earth embankment top surface shall be at least 0.5m higher than the designed static water level. 6.3.4 The earth embankment shall reserve settlement. The settlement can be determined based on analysis of factors such as the embankment base geology, embankment body soil quality and fill density, and should be 3% to 8% of the embankment height. When one of the following situations occurs, the settlement shall be calculated in accordance with the provisions of Section 8.3 of this Code. 1 The height of the earth embankment is greater than 10m;
2 The foundation of the embankment is a soft soil layer;
3 Non-compacted earth embankment;
4 Earth embankment with low compaction.
6.4 Earth embankment crest structure
6.4.1 The crest width of the embankment should be determined according to flood control, management, construction, structure and other requirements. The crest width of the 1st level embankment should not be less than 8m, the crest width of the 2nd level embankment should not be less than 6m, and the crest width of the 3rd level and below embankments should not be less than 3m. 6.4.2 According to the needs of flood control traffic, material storage, etc., a return yard, a lane avoidance, and a material storage yard should be set outside the crest width, and their specific layout and size can be determined according to needs.
6.4.3 According to the needs of flood control, management and mass production, a ramp should be set up on the embankment. The location, slope, crest width, structure, etc. of the ramp on the embankment can be determined according to needs. The ramp on the water side should be arranged in the direction of the water flow. 6.4.4 The pavement structure of the embankment top should be selected according to the requirements of flood control and management, and combined with the soil quality of the embankment body, meteorological conditions and other conditions. 6.4.5 The embankment top should be inclined to one side or both sides, and the slope should be 2% to 3%. 6.4.6 Due to the limitation of the soil source and site for embankment construction, a wave-breaking wall can be built. The structure of the wave-breaking wall can be made of dry stone joints, mortar stone, concrete, etc. The net height of the wave-breaking wall should not exceed 1.2m, and the burial depth should meet the requirements of stability and anti-freezing. The water-facing side of the wave-breaking wall of the sea embankment and lake embankment with strong winds and waves should be made with anti-wave curved surfaces. The wave-breaking wall should be equipped with deformation joints, and the strength and stability should be calculated. 264
6.5 Embankment slope and Qiantai
6.5.1 The embankment slope should be determined by stability calculation based on the embankment grade, embankment structure, embankment foundation, embankment soil quality, wind and wave conditions, slope protection type, embankment height, construction and application conditions. The slope of the 1st and 2nd grade earth embankments should not be steeper than 1:3.0. The slope of the waterside of the seawall should be determined according to its protection type. 6.5.2 The platform should be determined according to the needs of embankment stability, management, drainage and construction. For embankments with a height of more than 6m, a platform should be set up on the backwater side, and the width of the platform should not be less than 1.5m.
6.5.3 The waterside of seawalls and lake embankments with strong winds and waves should be equipped with a wave-breaking platform, the width of which can be 1 to 2 times the wave height, but should not be less than 3m. The elevation of the seawall wave-breaking platform can be the design high tide level or slightly lower than the design high tide level. For important seawalls, the elevation and size of the wave-breaking platform should be determined by test. The wave-breaking platform should be protected by mortar-laid large blocks of stone, vertical stone strips, cast-in-place concrete, etc. 6.6 Slope protection and slope drainage
6.6.1 The slope protection should be strong and durable, made of local materials, and conducive to construction and maintenance. Different types of slope protection can be selected for different sections of embankments or different parts of the same slope.
6.6.2 The type of slope protection on the water side should be determined based on the size of wind and waves, water flow near the embankment, tidal conditions, combined with factors such as the grade of the embankment, embankment height, embankment body and embankment foundation soil. For embankment sections with strong ship wave effects on navigable rivers, the slope protection design should take into account their effects and impacts. The type of slope protection on the back side should be determined based on the local rainstorm intensity, overtopping requirements, and combined with the embankment and soil conditions. 6.6.3 For 1 and 2 grade earth embankments with strong water flow scouring or wind and wave effects, stone masonry, concrete geotextile mold bag concrete slope protection should be used on the water side slope. Cement soil, turf and other slope protection can be used for the back slopes of 1 and 2 grade embankments and the water slopes of other embankments. 6.6.4 The structural dimensions of stone masonry slope protection should be calculated according to Appendix D of this code. For 1st and 2nd level embankments or 3rd level and below embankments with a commercial depth of less than 3m, the slope protection of the same type of embankments can be selected according to the existing slope protection. 6.6.5 A shark cushion must be set between the cement soil, stone masonry, and concrete slope protection and the soil. The cushion can be made of sand, gravel or crushed stone, slag and geotextile, and the thickness of the sand and gravel cushion should not be less than 0.1m. The slope protection cushion of seawalls and lake embankments with strong winds and waves can be appropriately thickened. 6.6.6 Cement soil, mortar masonry, concrete and other slope protection should be equipped with drainage holes, and the hole diameter can be 50~~100mm. The hole spacing can be 2~3m, preferably arranged in a plum blossom shape. Mortar masonry and concrete slope protection should be equipped with expansion joints. 6.6.7 For stone and concrete slope protection, a base should be set at the foot of the embankment, on both sides of the platform or wave-breaking platform or where the slope changes. The buried depth of the base at the foot of the embankment should not be less than 0.5m. The intersection of the slope protection and the top of the embankment should be firmly capped, and the capping width can be 0.5~1.0m. 6.6.8 The protection of the waterside of the seawall can adopt a slope type, steep wall type or composite structure, and should be determined by technical and economic comparison based on the embankment body, embankment foundation, water depth in front of the embankment, wind and wave size, materials, construction and other factors. The steep wall type should adopt a gravity retaining wall structure, and its cross-sectional size should be determined by stability and strength calculations. The masonry depth should not be less than 1.0m, and a transition layer should be set between the wall and the soil. The transition layer can be filled with gravel, crushed stone or slag, and its thickness can be 0.5~1.0m. The composite slope protection should be combined with a platform for slope change, and the length of the platform should be determined according to the requirements of wave breaking. 6.6.9 Concrete or reinforced concrete special-shaped blocks should be used for the protection of the water-side slope of the seawall where wind and waves are strong. The structure and layout of the special-shaped blocks can be determined by calculation according to the requirements of wave dissipation. Important sections of the embankment should be determined through tests. 6.6.10 When the earth embankment higher than 6m is severely eroded by rainwater, drainage facilities should be installed on the embankment top, embankment slope, embankment foot, and the junction between the embankment slope and the hillside or other buildings.
6.6.11 Drainage ditches parallel to the axis of the embankment can be set on the inner side of the platform or near the embankment foot. Vertical drainage ditches on the slope can be set every 50~~100m and should be connected with drainage ditches parallel to the axis of the embankment. Drainage ditches can be built with precast concrete or block stone masonry. Their size and bottom slope should be determined by calculation or combined with the experience of existing projects. 6.7 Anti-seepage and drainage facilities
6.7.1 The structural type of anti-seepage of the embankment should be reasonably determined based on seepage calculation and technical and economic comparison. 265
The anti-seepage of the embankment can be achieved by core wall, inclined wall and other types. The anti-seepage materials can be clay, concrete, asphalt concrete, geomembrane and other materials. The drainage of the embankment can be achieved by extending into the backwater slope foot or adhering to the slope filter layer. The filter layer material can be sand, gravel or geotextile and other materials. 6.7.2 The anti-seepage body of the embankment should meet the requirements of seepage stability and construction and structure. 6.7.3 The layout of the anti-seepage and drainage body of the embankment should be coordinated with the anti-seepage and drainage facilities of the embankment foundation, and the two should be closely integrated. 6.7.4 The top of the anti-seepage body should be 0.5m higher than the design water level. 6.7.5 The cross-section of the soil anti-seepage body should be gradually thickened from top to bottom. The minimum horizontal width of the top should not be less than 1m, and the bottom thickness should not be less than 1/4 of the design water depth in front of the embankment. The thickness or top width of the sand and gravel drainage body should not be less than 1m. 6.7.6 A protective layer shall be provided on the top of the earth impermeable body and the water-facing side of the inclined wall. The thickness of the protective layer shall not be less than the local freezing depth. 6.7.7 Asphalt concrete or concrete impermeable bodies may be in the form of panels or core walls. A cushion or transition layer shall be provided between the impermeable body and the fill body.
6.7.8 When geomembranes and geotextiles are used as impermeable and drainage materials for earth-rock embankments, their performance shall meet the requirements of strength, permeability and anti-aging. The surface shall be protected.
6.8 Flood walls
6.8.1 Flood walls shall be used in areas where the construction of earth embankments is restricted, such as cities and industrial and mining areas. Reinforced concrete structures shall be used for flood walls. When the height is not large, concrete or mortar-stone structures may be used. The top elevation of the wall shall be calculated and determined in accordance with Article 6.3.1 of this Code. 6.8.2 Flood walls shall be calculated for anti-tilting, anti-sliding and overall foundation stability in accordance with the provisions of Chapter 8 of this Code. The foundation stress should meet the requirements of the foundation's allowable bearing capacity. When the foundation bearing capacity is insufficient, the foundation should be reinforced. 6.8.3 The flood wall should meet the strength and anti-seepage requirements. The structural strength calculation should be carried out in accordance with the relevant provisions of the current national standard "Design Code for Hydraulic Concrete Structures". The base seepage profile should meet the foundation seepage stability requirements. 6.8.4 The buried depth of the flood wall foundation shall meet the requirements of anti-scouring and anti-freezing depth. 6.8.5 Expansion joints shall be set up in the flood wall. The joint distance of reinforced concrete wall should be 15~20m, and that of concrete and mortar-made stone wall should be 10~~15m. Expansion joints shall be added where the foundation soil, wall height, external load and wall section structure change. Waterstops shall be set up in the expansion joints. 7 Bank protection
7.1 General provisions
7.1.1 Protective measures shall be taken for the sections of the bank that may be scoured and damaged by wind, waves, water flow and tides. The design of the bank protection project shall be comprehensively considered and reasonably laid out, and a protection method combining engineering measures with biological measures shall be adopted. 7.1.2 According to factors such as wind and waves, currents, tides, ship wave effects, geology, topography, construction conditions, and application requirements, the following types of embankment protection projects can be selected:
1 Slope-type revetment,
2 Dam-type revetment;
3 Wall-type revetment,
4 Other types of protection.
7.1.3 The structure and materials of embankment protection projects shall meet the following requirements: strong and durable, strong anti-scouring and anti-wear performance, 1
2 Strong ability to adapt to riverbed deformation;
3 Easy to construct, repair, and reinforce;
Use local materials and be economical and reasonable.
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